harmony 鸿蒙CanvasGradient

2022-08-09
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CanvasGradient

CanvasGradient provides a canvas gradient object.

NOTE

The APIs of this module are supported since API version 8. Updates will be marked with a superscript to indicate their earliest API version.

addColorStop

addColorStop(offset: number, color: string): void

Adds a color stop for the CanvasGradient object based on the specified offset and gradient color.

Since API version 9, this API is supported in ArkTS widgets.

Parameters

Name	Type	Mandatory	Default Value	Description
offset	number	Yes	0	Relative position of the gradient stop along the gradient vector. The value ranges from 0 to 1.
color	string	Yes	’#ffffff’	Gradient color to set. For details about the color notation, see the description of the string type in ResourceColor.

Example

// xxx.ets
@Entry
@Component
struct Page45 {
  private settings: RenderingContextSettings = new RenderingContextSettings(true)
  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings)

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {
      Canvas(this.context)
        .width('100%')
        .height('100%')
        .backgroundColor('#ffff00')
        .onReady(() => {
          let grad = this.context.createLinearGradient(50, 0, 300, 100)
          grad.addColorStop(0.0, '#ff0000')
          grad.addColorStop(0.5, '#ffffff')
          grad.addColorStop(1.0, '#00ff00')
          this.context.fillStyle = grad
          this.context.fillRect(0, 0, 400, 400)
        })
    }
    .width('100%')
    .height('100%')
  }
}

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